A Facebook post featuring a meme with an image of Albert Einstein says that “people are being diagnosed with Delta variant even though there is no Delta variant test”.
This isn’t quite right. Although there are no direct Delta variant tests, PCR tests that are positive for SARS-CoV-2 can undergo genetic analysis such as ‘genomic sequencing’ which tells us if it is the Delta (or another) variant. This means it is possible to accurately identify if someone is unwell with the Delta variant of Covid-19.
What are variants?
All viruses mutate over time, creating changes to their genetic material, and the SARS -CoV-2 virus (the virus that causes Covid-19) is no exception.
These alterations to genetic material cause variants. Most changes will make little difference in how the virus behaves, but some may cause alterations in features such as transmissibility, severity or ability to evade vaccines.
It is these variants, such as the Delta variant, that may become known as ‘variants of concern’ or ‘variants of interest’.
How do you test for variants?
A test for Covid-19 shows whether an individual has SARS-CoV-2 or not (with some caveats such as the timing of the test, or how well a swab was taken).
A positive test can then undergo genomic sequencing, which the Department of Health and Social Care (DHSC) describes as “laboratory analysis that identifies a virus’s genetic make-up”. This is important because it allows “new variants or mutations in existing variants to be detected”.
Initially, in the UK, genomic sequencing was only being done to small samples of Covid-19 tests. A Public Health England (PHE) blog says that early on in the pandemic, sequencing would only be completed on approximately 5% of tests. However, at the start of July the government announced that more than 600,000 positive Covid-19 samples have now been genomically sequenced.